Lifting-magnet



" )STAInspra-TENT'- oFFicn :naar acmssmenn, or New vonk, n. Y.

Lrrrmnaanm. 1,333,542. Speculation el Lettmlatent. i Patented Mar. 9,1920.

' 'I l Application llled .'Tuly l, 191B. Serial No.2'42,95. p To all'inkom'. it may concern: polar extensions. in the ordinary 'forms of Beit known that I, Hannr G. Gnxsemonn, a citizen of the United States,residing at New, York, in4 thencounty of New York and State offNew York,have invented certain new and useful Improvements in Lifting- Magnets,of which t e following is a specication.

This invention relates to lifting or pulling magnets provided with anarmature thle movement of which through a predlltermined air gap isutilized to perform work.

Everyelectro-magnet has two airgaps in the magnetic circuit and in themajority of cases,"r'e resented by the Vplunger type, only one of e gapsis utilized to exert a tractive e'ort but the other gap, due to itsmagnetic reluctance, absorbs ai certainproportion of. the energy oft'flemagnetizing`"coil.

The .bbject of my inventiofn is -toxprvide a construction. which greatlyre uces the magnetic reluctance of the idle prior constructions and tosecure t e greatest tractive ellortpwith the minimum expend itune-ofelectrical energynf 'j Y,

The tractive elifort exerted between "two poles or across a variablgap,with the number of lines of force fer unit area. r'emaining thesame, depends "upon the square of themagnetio force across the gap andthe square-of the diameter of the gap. If the reluctance of the idleVgap is equal to that ofthe tractive gap, the magnetic force actin acrossthe active" a would be represented` by 0.5, and the traciive eil'ort by0.25 of the pull, which would beexerted if there ,were no idle gap,neglectin `of course the slight amount absorbed by t c reluctance of theiron of the magnetic circuit. This represents the best practice inmagnetic structures. If the re uctance of the idle gap is reduced to onequarter o f'that of the active ga the magnetic force at the active fpolewiil be 0.8 and the tractive e'ort 0.64 o theoretical magneticstructure..

From lthe vfore oing facts re arding magnetic 4structures 1t is evidentt at the tractive ell'ort is increased by increasing ythe diameterofitlie pole or lines of force per unit area remaining the same. `@wingto mechanical diiculties of increasing the area of the polesby means ofp :over

the

gap, the number of weight. These several advantageous features are ofimportance where small forces arc available.

Myrinvention will be understood from thc following detailed descriptionin connection with the'aocompanying drawing, which rcpi rcscnts alongitudinal vertical sectional vicw of a lifting or traction magnetvembodying the features claimed.'

a Aminimum of space and permits the use of an amature of mlnlmum Themanietic .structure4 comprises a, cylindrical she l or casing 2, havingan aperture in its closed end intov which the core `3 is threaded orotherwise secured, the lower or polar end having an extension 3. Thebase 5,.also of magnetic material, is preferabl threaded totheouterannular rim of the sliiell and is rovided with an inwardlyprojecting cylin rical extension 6, which is cupped or hollowed out toform an annular lip or ring portion7 said cylindrical extension formingwith the throat portion 2 of the shell, an annular air p -9. The arma,-ture 10 may be convenlently formed by drawing a disk of magneticmaterial into the shape of a shallow cup, the annular flange portion 10'extending gap 9, which constitutes the'idle gap of the ma ctic circuit.The armature may be attache to a boss 12, carried by an operating stem14. The stem may be connected in any suitablemanner to a valve, switch,or any other mechanism to be actuated. It

into the annular a1r- :s shown as sliding through the core 3 and basemember 5, but it is evident thatit may only slide within the'co're ifdesired, depending upon the duty of the magnet. In fact, this ma ncticstructure can be readily made air tigt and the armature stem may act asthe valve stem where the valve seat is made e. part of the magneticstructure. The energizing coil or winding '15 surrounds the core usualand may be supported upon the polar extension 3. The terminals othe'coil may be connected to binding posts or bolts 17,4 which pasethrough in-l sulating bushinps locatedin apertures in the wall of theshel It will be understood by those familiar with magnetic devices thatthe lines of force or magnetic tlux generated bv the current ilowing inthe energizing coi 15, traverse the core, spread out through the golepiece 3', bridge the active ga 8, an thereby create a stress or pull wich results in lifting the armature to the le. piece. The lines of forcespread out ra ially in the armature,

assing into the annular llangel and then ]umping the double gap inopposite directions to the cylindrical base extension and the neck ofthe shell respectively, the lines completing the circuit through theshell to the core.

It is apparent that the degree of saturation of the armature is uniformthroughout the diameter of the pole and only decreases to zero in theannular flange or liplO, and

hence the mass or weight of the armature is A ellectively used incarrying the ilux lines.

In 'actual constructionY the armature may readilyl be formed with theflange or li portion about equal in height bo one-thir of the diameterof the top or main body pottion, or to provide a flange area within theannular idle gap between the base and shell,

about equal to twice the area of the pctive polar gap between the top ofthe' rmature and th pole piece. The clearance between the annular lip ofthe armature andthe opposite walls of the annulargap can usually bereduced to one half the lengthi ofthe active polar gap: so that, as inthe example taken above, the reluctance of the idle gap would be onequarter of that of the active gap, The oppositely acting stresses in theannular idle gap arobalanced and therefore neither add to nor subtractfrom the trartive eli'ort of the magnet. The

small stressin the gap between the top-edge 7 of the cylindrical lip ofthe base extension and the under side of 'the armature is so slight asto be practically negligible as will be -apparent from a considerationof the relation of parts. The distance between the magnetic reluctanceofthe several paths or' lip edge 7 and the armature is at least twice asgreat as the distance laterally or radially in the annular gap from thearmature flange to the walls of the gap. ANow, the distribution of ux isinversely as the length of the gap. If the vertical gap distancebe twicethe radialgap distance and the edge surface 7'* of the lip is one-eighthof the' armature surface extending within the annular gap, than theproportion of linxv lines between the lip edge and the lowerside l orlith of that of the active of the armature would be one-sixteenth ofthat passing through the annular gap or the active ga The pull o f themagnet is in proportion to the square of the lux lines area ol the gapAs the area of the li edge gap is one-quarter of that of the wor inggap, the dowpward,

or negative pull wouldbe equal to and changesv may be made"without-'depart ing from my invention; I claim 1.I A liftingor magneticstructure provided with-an active gap across which thetractive eort isexerted and an idle-gap, and 'an 'armature operative traction magnethaving a within the active gap`and having Ian o'set44 portion extendingwithin .the idle gap.v 's 2. A liftingor traction migmet 'havmgal rovded,with anactive magnetic structure gap across which t atractivaeil'ort-isen erted and an annular idle gap` and an artig ture operativewithin the active gapjaiid having an 'annular oil'set lip portionorfiange proiecting into the idle php5.

B. A lifting ortraction magnetliaying Y magnetic structure provided4with a. shell portion constituting-the return for the maig-- neticcircuit` a pole piece extending inwardly `from the closed rinner volteend ofthe shell;i

and an armature operative in theamctivegap in front of the pole pieceandiifli'aving an odset lip portion extending' adjacent the inner wallof the outer end ofthe shell, the

ins

space between said lip and said inner shell wall constituting an idlegap.

4'. A traction inagnethavim! structure provided with a 4shell portion. acore portion extendinginwardlv from the inner yoke end cnt .the' shelland having-iin enlarged pole niece. an' energizing winding'sm-rounding'the core portion,a p' ber fitting within the outer end ofthe shell and having an inwardlvproiecting part ex 4tending adiacenttheinner shell wall. the

annular space therebetween constituting the a maimeti base themidle gap`and an armature operative'in front 1,sss,a42 8 of the pole piece andhaving a anged anand a cup-sha ed armature having the annular lip orskirt portion extending within nular side or iip portion extendingWithin said idle gap. l said annular space and the main body por- 10 5.A traction magnet of the shell type tion operative within the activegap.5 having a closed magnetic circuit provided In testimony whereof I affixmy signature.

"With" interior active and idle gaps, the laty ter being in the form ofan annnlai` space, HARRY G. GEISSINGER.

